This application claims the benefit of a Japanese Patent Application No.11-375799 filed Dec. 28, 1999, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to location managing methods for managing locations of mobile stations in mobile wireless packet communication systems and mobile wireless packet communication systems, and more particularly to a location managing method which hierarchically manages located cell information and registered location information of mobile stations in a mobile wireless packet communication system, and to a mobile wireless packet communication system which employs such a location managing method.
2. Description of the Related Art
In conventional mobile wireless packet communication systems, a home location register (HLR) manages location information which indicates a cell of a base station in which each of mobile stations are located, and a route for a packet addressed to each mobile station is determined based on this location information. In other words, the location information such as located cell information of the mobile stations is centrally managed by the HLR.
However, in such wireless packet communication systems, the routes of the packets addressed to and sent to the mobile stations are searched for each of the users (transmitting destinations). For this reason, when the location information is centrally managed by the HLR as described above, the load on the HLR when searching the routes increases as the number of users increases and the traffic increases.
In addition, when the location information is updated during a handover of the mobile station, the load on the HLR when updating the location information also increases as the number of users increases and the moving frequency of the mobile station increases.
Furthermore, because the location information of the mobile station must be read from the HLR, a delay is generated in the route searching due to the increase of the data traffic and the increased size of a routing table which result from the increase of constant connection type users.
Accordingly, it is a general object of the present invention to provide a novel and useful location managing method for managing a location of a mobile station in a mobile wireless packet communication system, and a mobile wireless packet communication system, in which the problems described above are eliminated.
More particularly, a first object of the present invention is to provide a location managing method for managing a location of a mobile station in a mobile wireless packet communication system, which can reduce a processing load when searching routes of mobile stations and updating location information.
Further, a second object of the present invention is to provide a mobile wireless packet communication system which is applied with the above described location managing method for managing the location of the mobile station.
Still another object of the present invention is to provide a location managing method for managing a location of a mobile station in a mobile wireless packet communication system in which each of communication nodes down to base stations have a hierarchical structure, wherein a route from a communication node positioned at a highest layer of the hierarchical structure to a base station of a cell in which the mobile station is located, is managed as location information of the mobile station, by being distributed to the communication node located at the highest layer of the hierarchical structure and to each of communication nodes in the route to the base station. According to this location managing method for managing the location of the mobile station, when the mobile station moves to another cell of another base station, only communication nodes in a differing route portion between the route to the base station of the cell in which the mobile station was located before the move and the route to the other base station of the other cell to which the mobile station moves need to modify route management with respect to the mobile station, because the route from the communication node positioned at the highest layer of the hierarchical structure to the base station of the cell in which the mobile station is located is managed as the location information of the mobile station by being distributed to the communication node located at the highest layer of the hierarchical structure and to each of communication nodes in the route to the base station. Therefore, the first object described above is achieved.
From the point of view of providing a particular distributed management, in the location managing method for managing the location of the mobile station, each of the communication nodes may manage a portion of the route from the communication node positioned at the highest layer of the hierarchical structure to the base station of the cell in which the mobile station is located, in correspondence with the mobile station.
From the point of view of providing a simpler management, in the location managing method for managing the location of the mobile station, each of the communication nodes may manage a communication node positioned in an immediately lower layer and the mobile station in correspondence with each other. According to this location managing method for managing the location of the mobile station, only the route portion between each communication node and the communication node positioned in the immediately lower layer is managed by each communication node.
In order to carry out the route management at each of the communication nodes when the mobile station moves between cells, in the location managing method for managing the location of the mobile station, when the mobile station moves to an other cell of an other base station, of each of communication nodes positioned in layers higher than that of the other base station of the other cell, a communication node which does not manage a portion of a route to the other base station of the other cell may newly manage the portion of the route in correspondence with the mobile station. According to this location managing method for managing the location of the mobile station, of each of the communication nodes positioned in layers higher than that of the other base station of the other cell, the communication node which does not manage the portion of the route to the other base station of the other cell newly manages the portion of the route in correspondence with the mobile station. In this case, no new route management is carried out in the communication node which already manages the portion of the route to the other base station of the other cell.
In order to minimize the communication traffic, in the location managing method for managing the location of the mobile station, the mobile wireless communication system may make the paging with respect to the mobile station from a plurality of base stations under control of a predetermined communication node, and when the mobile station in a reception waiting state moves between cells of the plurality of base stations, managing contents need not be modified in each of communication nodes positioned in layers higher than that of the base station of the cell to which the mobile station moves. According to this location managing method for managing the location of the mobile station, when the mobile station moves among the plurality of base stations which make the paging, the management contents at each of the communication nodes are not modified even when the route of the communication nodes changes due to the move. For this reason, no communication is made among each of the communication nodes due to the modification of the management contents. In this case, when the paging is made with respect to the mobile station, it is sufficient to modify the management in each of the communication nodes position in the layers higher than that of the base station which actually communicates with the mobile station, for example.
A further object of the present invention is to provide a mobile wireless packet communication system wherein each of communication nodes to a base station form a hierarchical structure, a route from a communication node positioned at a highest layer of the hierarchical structure to a base station of a cell in which a mobile station is located, is managed as location information of the mobile station, by being distributed to the communication node located at the highest layer of the hierarchical structure and to each of communication nodes in the route to the base station, and a packet addressed to the mobile station is successively transferred from the communication node in the highest layer to the base station depending on the route which is distributedly managed, so as to transfer the packet from the base station to the mobile station by a wireless communication. According to the mobile wireless packet communication system of the present invention, it is possible to achieve the second object described above.
In the mobile wireless packet communication system, each of the communication nodes may be provided with a routing table which manages a portion of the route from the communication node positioned at the highest layer of the hierarchical structure to the base station of the cell in which the mobile station is located, in correspondence with the mobile station.
In the mobile wireless packet communication system, the routing table provided in each of the communication nodes may manage a communication node positioned in an immediately lower layer and the mobile station in correspondence with each other.
Furthermore, in the mobile wireless packet communication system, when the mobile station moves to an other cell of an other base station, of each of communication nodes positioned in layers higher than that of the other base station of the other cell, a communication node which is provided with a routing table which does not manage a portion of a route to the other base station of the other cell may update the routing table so as to newly manage the portion of the route in correspondence with the mobile station.
In the mobile wireless packet communication system, a plurality of base stations under control of a predetermined communication node may make the paging with respect to the mobile station, and when the mobile station in a reception waiting state moves between cells of the plurality of base stations, the routing table need not be updated in each of communication nodes positioned in layers higher than that of the base station of the cell to which the mobile station moves.
In order to prevent the packet addressed to the mobile station which assumes a communication state from being transferred to the base station of the cell in which the mobile station was located before the move when the mobile station moves to another cell, in the mobile wireless packet communication system, when the mobile station which assumes a communication state with the base station moves to another cell of another base station, each of communication nodes in a route from a common communication node which is common to a route to the base station of the cell in which the mobile station was located before the move and a new route to the other base station of the other cell to the base station of the cell in which the mobile station was located before the move may delete from a routing table thereof management information of a route portion from the common communication node to the base station of the cell in which the mobile station was located before the move.
In addition, in order to positively transfer the packet addressed to the mobile station and already transferred to the mobile station to the communication node in the original route to the base station before the move at the time when the management of the new route to the other station of the other cell to which the mobile station moves starts, in the mobile wireless packet communication system, each of communication nodes positioned in layers lower than the common communication node and in the route from the common communication node to the base station of the cell before the node, may return the packet addressed to the mobile station to the common communication node. In this mobile wireless packet communication system, the packet addressed to the mobile station is returned to the common communication node, and thus, the packet can successively be transferred to the mobile station via the new route from the common communication node.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.